1. Field of the Invention
The present invention relates to a microscope such as an industrial microscope or the like.
2. Related Background Art
With an increased demand for optical microscopes of high resolving power in recent years, shortening of a wavelength to be used has progressed.
Constitution of a conventional microscope is simply explained as follows. An illumination light emitted from a light source is transmitted through an illuminating lens, and then made incident on a half mirror. A part of the illumination light made incident on the half mirror, which has been reflected by the half mirror, is transmitted through an objective lens to illuminate a sample placed on a stage. Assuming that a direction of an optical axis is Z and two directions orthogonal to each other on a plane are X and Y, the plane being orthogonal to the Z direction, the stage can be moved in the X, Y and Z directions by a stage driving system.
An observed light reflected on the sample is transmitted through the objective lens, and then made incident on the half mirror. After having passed through the half mirror, the observed light is transmitted through an image-forming lens to form an image on an image sensor. An output signal from the image sensor is converted into a video signal by a video signal processing circuit, and then transferred to a monitor. Thus, an image of the sample is displayed on the monitor.
In such a conventional microscope, when an observer watched the image of the sample placed nearly in a static state for a long time, the sample was continuously irradiated with illumination lights, and damage such as deformation, discoloration or the like occurred in the sample. The damage can be attributed to a gradual increase in energy of a light projected to the sample. Such a phenomenon was especially conspicuous in a laser-scanning microscope for converging illumination lights in a very small spot.
Light energy on the sample, i.e., a quantity of an illumination light to be projected, can be obtained by a product of illuminance and irradiation time. A damage degree of the sample has a correlation with this quantity of the illumination light to be projected. In other words, with an increase in the quantity of an illumination light to be projected, a damage of the sample is larger. With a reduction in the quantity of the same, a damage is smaller. If a damage of the sample is large, not only reproducibility will be reduced when the sample is observed again and measured but also a quality of the sample as a product will be reduced. If the sample is a living being such as a microorganism, the living being may die.
It is an object of the present invention to provide a microscope capable of reducing damage such as deformation, discoloration or the like given to a sample.
In accordance with a first aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; a display for displaying an image of the sample based on a video signal from the processing unit; and an illuminance reducing unit for reducing illuminance of the illumination light on the sample to be lower than a specified value enough for observation by the display. With this microscope, by operating the illuminance reducing unit at a specified timing according to conditions including a movement of the stage or the like, it is possible to prevent inconveniences such as damage given to the sample by an excessive quantity of illumination light made incident on the same.
In accordance with a second aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; a stage driving system for driving the stage; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; and a monitor for displaying an image of the sample based on a video signal from the processing unit. The microscope further comprises illuminance reducing means for reducing illuminance of the illumination light on the sample, and is characterized in that assuming that a time width where illuminance is at a level enough for displaying an image of the sample is TF, and a time width where illuminance is lower than the level for displaying an image of the sample is TN, and a value a is as follows:
xcex1=TF/(TF+TN)xe2x80x83xe2x80x83(1)
the value xcex1 is changed by the illuminance reducing means according to a velocity of the stage, and the monitor (or display) displays a still picture of the sample for a period of TN, the still picture being one before the time width TN.
In this case, the illumination reducing means can set the value xcex1 to 0 while the stage is stopped, and to 1 while the stage is on the move.
With the foregoing constitution, since the irradiation quantity of illumination light in the same sample face is reduced, damage given to the sample is reduced. Next, an operation of the microscope of the invention will be described in detail. Generally, a sample placed on the stage of the microscope such as an industrial microscope is a static object. In other words, the sample unless a microorganism or the like never moves around itself.
Thus, while the stage where the sample has been placed is stopped, no change occurs in an image of the sample displayed on the monitor. Even while the stage is not completely stopped, if a velocity of a movement thereof is relatively low, a latest still picture may be displayed on the monitor while updating the same. In this way, a state is realized, which is nearly the same as that of displaying a motion picture (live image) of the sample in real time.
For example, consideration is given to a case where while the stage is in a stopped state, in other words while a stage velocity is 0, a monitor screen is frozen (fixed) without displaying the motion picture of the sample on the monitor, and the still picture of the sample is displayed. In this case, the stage is stopped and, at the instant of the stoppage thereof or after the passage of specified time, illuminance of an illumination light reaching the sample is reduced. As a result, damage given to the sample can be prevented.
On the monitor (or display), an image immediately before reduction of the illuminance is displayed as a still picture. In other words, the monitor screen is made frozen. Thus, no inconveniences occur for observation or measuring.
On the other hand, if the movement of the stage is started again, the illuminance of the illumination light reaching the sample is immediately restored to a normal value, and a motion picture of the sample is displayed on the monitor.
Here, the stopped state of the stage means that no displacement occurs in the stage not only in directions (X, and Y directions) orthogonal to an optical axis but also in a direction of the optical axis (Z direction). Thus, since the stage is not in a stopped state in a step of searching a desired position on the sample (moving step in X and Y directions) or in a step of adjusting a focus position (moving step in Z direction), the motion picture is displayed on the monitor. After the above operations are finished, then the stage is placed in a stopped state for the first time, and the still picture is displayed on the monitor.
Displacement of the stage can be easily detected by using a displacement gauge such as an encoder, an interferometer or the like. Also, in the case of using an electric stage, stage displacement can be detected based on existence of an operation of a stage driving motor.
Furthermore, reduction of the illuminance of the illumination light reaching the sample can be achieved by reducing an output of the light source or stopping the same. This can also be achieved by using a shutter to cut off the illumination light. Other than these, the illumination light may be cut off by using polarization to rotate a polarizing plate or a wavelength plate, alternatively by electrically modulating a liquid crystal wavelength plate.
Thus, with the present invention, according to a stage velocity v, the illuminance of the illumination light reaching the sample is adjusted, in other words, the value a in the expression (1) is changed.
In accordance with a third aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; a stage driving system for driving the stage; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; and a monitor for displaying an image of the sample based on a video signal from the processing unit. The microscope further comprises: illuminance reducing means for reducing illuminance of the illumination light on the sample; and a switch for performing switching between a continuous mode and an intermittent mode, the continuous mode being for displaying a video signal as a motion picture on the monitor, the video signal being one when illuminance is at a level enough for displaying an image of the sample, and the intermittent mode for a video signal as a still picture on the monitor while updating the same by using the illuminance reducing means to intermittently reduce illuminance, the video signal being one immediately before illuminance is set lower than the level enough for displaying an image of the sample.
In this case, the microscope further comprises displacement detecting means for detecting the displacement of the sample, and it is preferred that when the sample is displaced, the continuous mode should be set irrespective of a position of the switch.
With the foregoing constitution, damage given to the sample can be reduced by reducing an irradiation quantity of illumination light for a sample face. Next, an operation of the microscope of the invention will be described in detail. Generally, in any fields, an industrial field, a biological field or otherwise, with the microscope, since observation accuracy must be maintained for image observation, illuminance should not be reduced unnecessarily. As described above, however, an observer may need to observe an image of the sample placed in a near static state for a long time.
Thus, if the observer determines no necessity of continuous illumination or image capturing (continuous mode), by using the switch to make switching to the intermittent mode for intermittently performing illumination and image capturing, an irradiation quantity to the sample is reduced and, accordingly, damage given to the sample can be prevented. Subsequently, when an image is changed every moment, for example the sample is moved or, a focus is changed, the intermittent mode may be changed to the continuous mode by switching the switch. In this case, since cancellation of the intermittent mode depends on determination by the observer, priority is placed on relative sample damage reduction.
On the other hand, for placing priority on relative sample observation, detection may be performed for sample displacement, and the intermittent mode may be forcibly canceled when sample displacement is detected.
In accordance with a fourth aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light from the light source; a stage for placing the sample; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; and a monitor for displaying an image of the sample based on a video signal from the processing unit. The microscope is characterized in that a change amount of a video signal entered into the processing unit is detected, illuminance of the illumination light on the sample is reduced to a level for detecting the change amount of the video signal when the change amount of the video signal is smaller than a predetermined value, the video signal immediately before reduction of the illuminance is sent as a still picture to the monitor, the illuminance is set to the level enough for displaying an image of the sample when the change amount of the video signal is equal to the predetermined value or larger, and the video signal at this time is sent as a motion picture to the monitor.
With the foregoing constitution, an irradiation quantity of illumination light for the sample is reduced, and damage given to the sample can be reduced. Next, an operation of the microscope of the invention will be described in detail. In the microscope, illuminance should not be reduced unnecessarily for performing image observation. But an observer may need to watch an image of the sample placed in a near static state for a long time.
Thus, at the instant of this state or after the passage of predetermined time, by dimming the illumination light, damage given to the sample can be prevented. In this case, on the monitor, an image immediately before dimming is displayed in a frozen (fixed) manner. Accordingly, since no change occurs in the image, any inconveniences can be prevented for observation. Also, since the illuminance is reduced, damage given to the sample can be prevented.
Then, if a change occurs in the image, a screen on the monitor is immediately returned to a motion picture (live image).
In this case, for detecting changes in the image, image capturing is constantly executed. In other words, usually, image capturing and corresponding displaying on the monitor are both executed. During dimming, image capturing is executed, but no corresponding displaying is executed on the monitor. Then, determination is always performed as to existence of a change in the image by image capturing. If no image changes are determined, then image capturing in a dimmed state is continued. If an image change is determined, a motion picture is displayed on the monitor.
Thus, if there are no substantial changes in the image on the monitor, illumination of the sample is dimmed. If the image is changed every moment, for example during searching of a desired position on the sample, during adjusting of a focus position, while a living being as a sample is alive and moving or the like, a motion picture is always displayed on the monitor. Conversely, if the sample becomes static, for example when position adjusting, focus adjusting or the like is finished, the process changes to a dimmed state.
In this case, a unit constitution for detecting image changes should preferably include a memory for storing image data of a plurality of frames, and an electric processing system for comparing images with each other based on information thereof and determining a change.
In accordance with a fifth aspect of the invention, a microscope is disclosed, which comprises: a light source; an illumination optical system for irradiating a sample with an illumination light emitted from the light source; a stage for placing the sample; an image-forming optical system for collecting an observed light exiting from the sample; a detector for detecting the observed light passing through the image-forming optical system; a processing unit for processing a signal from the detector; and a monitor for displaying an image of the sample based on a video signal from the processing unit. The microscope further comprises: illuminance reducing means for reducing illuminance of the illumination light on the sample; and control means for detecting a change amount of the video signal entered into the processing unit and controlling the illuminance reducing means and the processing unit according to the change amount.
With the foregoing constitution, by reducing an irradiation quantity of illumination light to the sample face, damage given to the sample can be reduced. Next, an operation of the microscope of the invention will be described in detail. In the microscope, illuminance should not be reduced unnecessarily for performing image observation. But an observer may need to watch an image of the sample placed in a near static state for a long time. In such a case, substantially no changes occur in an image on the monitor.
Thus, at the instant of the above state or after the passage of predetermined time, by reducing illuminance of the illumination light, damage given to the sample can be prevented. At this time, on the monitor, an image immediately before the illuminance is reduced is displayed in a frozen (fixed) manner. In this way, since no changes occur in the image, any inconveniences can be prevented for the observer. Also, since the illuminance is reduced, damage given to the sample can be reduced.
Then, if any changes occur in the image, a screen on the monitor is immediately returned to a motion picture (live image).
In this case, for detecting an image change, short-time image capturing is performed at every constant interval of time even while the image is frozen. Then, determination is made as to a change in the image around this time interval. If no image changes are determined, then only intermittent image capturing is continued. If an image change is determined, then only continuous image capturing is carried out to return to the motion picture.
Thus, if there are no substantial changes in the image on the monitor, since the sample is illuminated intermittently, an irradiation quantity of illumination light is reduced. If the image is changed every moment, for example during searching of a desired position on the sample, during adjusting of a focus position, or while a living being as a sample or the like is alive and moving, the motion picture is always displayed on the monitor. Conversely, if the sample becomes static, for example when position adjusting or focus adjusting is finished, the process proceeds to an intermittent image capturing state.
A unit constitution for detecting image changes should preferably include, for example a memory for storing image data of a plurality of screens, and an electric processing system for comparing images with each other based on information thereof and determining a change.